It is described a method of estimating a rotor operational parameter (θ,ω) of an electrical
machine (3) comprising multiple winding sets (15a,15b,15c, 17a,17b,17c) wound to have a phase-shift between winding sets, the rotor operational parameter comprising rotor position (θ) and / or
rotor speed (ω), the method comprising: deriving, for each winding set (15, 17), a preliminary rotor operational parameter (39) based on a current (23) and a
voltage (27) of the respective winding set (15); calculating for at least two winding sets (15, 17) and for at least one predefined
harmonic (h), a rotor operational parameter
harmonic correction term based on the preliminary rotor operational parameter (39,θ1,ω1; 41,θ2,ω2) of at least two winding sets (15, 17); calculating for at least one winding set (15, 17), a corrected rotor operational parameter (11, 13, 12, 14) based on the preliminary operational parameter (39, 41) of this winding set and the rotor operational parameter
harmonic correction term of this winding set, wherein in particular the corrected rotor operational parameter has at least one predefined harmonic removed or at least attenuated.